The present invention relates to a temperature control system for controlling the temperature of an electronic device.
Advances in semiconductor technology have led to the development of a new generation of electronic devices, such as integrated circuits, having an increasingly larger number of active elements, higher circuit complexity, smaller area, and more closely spaced wiring. These attributes generate more heat in the electronic device and provide less opportunity for heat dissipation. This results in higher operating temperatures and consequently lower reliability, especially for integrated circuits that operate at high frequencies and high heat loads. The small size of the integrated circuit and the tightly packed electrical circuitry of surrounding equipment makes it even more difficult to cool the integrated circuit with conventional fans or heat sinks. In addition, the integrated circuits can experience large temperature fluctuations which affect their performance attributes, such as the timing of mathematical, data transfer, and read/write operations, especially at high frequencies. Variations in temperature of as little as .+-.5.degree. C. can cause a change in operating frequency of as much as 20 MHZ which significantly affects the performance of the chip. Thus, it is desirable to control the temperature of an integrated circuit during operation.
Prior art methods for controlling the temperature of an integrated circuit used a combination of heat sinks attached to the integrated circuit and cooling fans that directed a flow of air across the heat sinks. However, it is difficult to remove a large amount of heat by these methods. First, the thermal mass of the heat sink increases the time it takes for the integrated circuit to reach the desired temperature. Second, once the integrated circuit has been raised to its desired temperature, the relatively low specific heat capacity of air limits the ability of the cooling system to remove excess heat at a sufficiently high rate. It is particularly difficult for these temperature control systems to quickly respond to the large changes in temperatures that can occur in high performance chips.
Another problem associated with the prior art methods that occurs during testing of the integrated circuit chip is that the bulky heat sinks and cooling fans interfere with the operation of a robot handler that is used during testing. The robot handler has an articulated arm with a vacuum port to pick up an integrated circuit chip from a rack and hold the chip in a test socket. While power is applied to the integrated circuit, various read/write operations are performed on the integrated circuit. The robot handler remains in contact with the integrated circuit during testing. Typically, one or more heat sinks and cooling fans are attached to the arm of the robot handler which make the arm bulky and impede its ability to pick up individual integrated circuits and accurately position them in the test socket. Furthermore, the size of the heat sinks and cooling fans makes it difficult to retrofit existing robot handlers. Thus, it is desirable to have a temperature control system that is compact, lightweight, and which can be easily retrofitted to existing testing systems.
Thus, there is a need for a temperature control system that can maintain an electronic device at predetermined temperatures. It is also desirable for the temperature control system to rapidly raise and lower the temperature of the electronic device. It is further desirable for the temperature control system to be compact, lightweight, and adaptable for use with existing automated testers.